How to use the cat calorie calculator
- Enter your cat’s current weight.
- Choose its life stage and activity. Pick “Weight loss” to plan for a target weight, or “Custom” if your vet gave you a factor.
- Optionally type the kcal per can or pouch, or per cup of dry food, from the label.
- Read the daily calories and how many cans or cups that is.
The formula
Resting energy requirement (RER) = 70 × (body weight in kg)^0.75 kcal per day. This is the standard formula used by the NRC and WSAVA.
Daily calories = RER × a life-stage factor. The factors come from the Merck Veterinary Manual table of daily maintenance energy requirements:
| Cat | Factor |
|---|---|
| Spayed or neutered adult | 1.2 × RER |
| Intact adult | 1.4 × RER |
| Obesity prone | 1.0 × RER |
| Growing kitten | 2.5 × RER |
| Weight loss | 0.8 × RER at the target weight (AAHA 2021) |
Tips
- Weigh, don’t guess. A kitchen or baby scale gives a better number than a guess, and a change of half a pound matters for a cat.
- Check body shape. Use the cat weight calculator to find an ideal weight from your cat’s body condition score.
- Change slowly. Adjust portions by about 10% at a time and re-weigh every couple of weeks.
- Water counts too. Cats on dry food need to drink more; see the cat water intake calculator.
Sources
- Merck Veterinary Manual: Nutritional Requirements of Small Animals, table “Daily Maintenance Energy Requirements for Dogs and Cats”.
- AAHA 2021 Nutrition and Weight Management Guidelines for Dogs and Cats: 0.8 × RER at target weight for feline weight loss.
- NRC (2006) Nutrient Requirements of Dogs and Cats / WSAVA: RER = 70 × kg^0.75.
Frequently asked questions
How many calories should a cat eat a day?
It depends on weight and lifestyle. Using the Merck Veterinary Manual factors, a 10 lb (4.5 kg) spayed or neutered adult cat needs about 260 kcal a day (1.2 × its resting energy of about 218 kcal), and an obesity-prone cat about 218 kcal (1.0 × RER). Use your cat’s body shape as the final check and adjust by about 10% at a time.
How many calories should a cat eat to lose weight?
The AAHA 2021 Nutrition and Weight Management Guidelines suggest starting at about 0.8 × the resting energy for the cat’s target weight. For a cat aiming for 9 lb that is about 161 kcal a day. Cats should lose weight slowly, about 0.5–2% of body weight a week, and a cat that stops eating can become seriously ill, so plan weight loss with your vet.
How many calories are in a can of cat food?
It varies a lot by brand and recipe, so read the label: US cat foods list calories as kcal per can or per cup, and per kg. Type the number on your food into the calculator to see how many cans or cups give the daily calories.
Do kittens need more calories than adult cats?
Yes. Growing kittens need about 2.5 × their resting energy, according to the Merck Veterinary Manual, which is roughly twice what a neutered adult of the same weight needs. Feed a food made for growth and follow your vet’s advice.
How many treats can my cat have?
Keep treats to no more than about 10% of the day’s calories, the common veterinary rule, so the main food still supplies balanced nutrition. The calculator shows that 10% figure.